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Article Dans Une Revue Carbon Année : 2014

Graphitization at low temperatures (600-1200 °C) in the presence of iron implications in planetology

Résumé

Our objective is to understand how graphite can be formed at "low" temperatures (<1200 °C) in contrast to the high temperature of the industrial processes (∼3000 °C), and from precursors which are non-graphitizable by a thermal treatment alone. Blends of iron and saccharose char were heated between 650 and 1600 °C. The carbons obtained were characterized by SEM, TEM and Raman microspectrometry. Our work confirms that graphite can be formed from non-graphitizable carbons during a heat-treatment in the presence of iron. Carbon and iron migrations, below the eutectic temperature (1150 °C), appear to be a key factor for carbon transformation. Iron migration and graphitization could be favored by nucleation of Fe nanoparticles and surface melting, detected as soon as 900 °C. This allows formation of turbostratic macroporous carbons. Above the eutectic, all iron is liquid and graphitization occurs; it is complete at 1600 °C. Heat-treatment duration, observed over 4 orders of magnitude, favors the structural improvement. Concerning applications in planetology these experimental samples are pertinent experimental analogues of natural carbons from differentiated parent-bodies (with an iron core), and explain how graphite can be formed at temperatures below 1200 °C in these environments.
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Dates et versions

hal-00968173 , version 1 (31-03-2014)

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E. Charon, J.-N. Rouzaud, J. Aleon. Graphitization at low temperatures (600-1200 °C) in the presence of iron implications in planetology. Carbon, 2014, 66, pp.178-190. ⟨10.1016/j.carbon.2013.08.056⟩. ⟨hal-00968173⟩
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